The invention relates to a process as well as a system for setting controller parameters of a state controller.
State controllers have the advantage that with suitable parameterization a high control quality is achievable. In particular, with respect to the widely distributed PID controllers, a significantly better control behavior is achievable.
From A. Bunzmeier""s xe2x80x9cEin praxisorientiertes Inbetriebnahmekonzept fxc3xcr Zustandsregler im Bereich der Dampftemperaturregelungxe2x80x9d [A Practice-oriented Start-up Concept for State Controllers in the Field of Steam Temperature Control], VGB Kraftwerktechnik [VGB Power Plant Technology] 76, 1996, Volume 11, Pages 911 to 917, a state control with a start-up concept for the control of a steam superheater is known.
A difficulty of state controlling lies in the fact that, in general, significant skill in the art is required to parameterize a state controller so that a desired control behavior is achieved. The poles underlying a closed control circuit having a plant and a state controller, in a representation of the poles in a complex frequency range plane, are determinative for the control behavior of the control circuit. These poles are determinable by the parameterization of the state controller. Thereby it is difficult to judge the prospective control behavior from the controller parameters or the poles. In particular, extensive relevant skill in the art is required.
It is one object of the invention to improve the setting of controller parameters of a state controller, to achieve the desired control behavior of the closed control circuit.
According to one formulation, the invention is directed to a process for setting controller parameters of a state controller wherein, in a first step, a monitor and a basis state controller are arranged to form the state controller. Next, the state controller and a plant are arranged to form a closed control circuit, wherein the closed control circuit has at least one pole and one zero that are represented in a complex frequency range plane. Measuring indices are output from the plant to the monitor. The monitor generates, from these measuring indices, estimated control values which are supplied to the basis state controller. The controller parameters of the state controller are set with a controller setting apparatus to optimize a control behavior of the closed control circuit such that the at least one pole is shifted approximately along semi-circular arcs and/or rays originating from the origin in the complex frequency range plane.
According to another formulation, the invention is directed to a system associated with the process just described. The system includes a plant to output the measuring indices, a monitor to receive the measuring indices and to output estimated control values, a basis state controller to receive the estimated control values from the monitor, and a controller setting apparatus to set the controller parameters of the state controller to optimize and fine tune the control behavior of the closed control circuit.
It is one advantage of the process according to the invention that the controller parameters of the state controller are modifiable only in such a way that, in a representation of the poles of the closed control circuit in a complex frequency range plane, the setting causes a shift of the poles approximately along semi-circular arcs and/or along rays from the origin.
Another particular advantage is that the invention adjusts the control parameters of the state controller by providing, in advance, control parameters that are easily understood and recognized from a control-technological standpoint. Proceeding from a base setting of the state controller, a fine-tuning of the closed control circuit, which is based on the base setting, can be accomplished without particular control-technological expertise. The base setting is, for example, a coarse preliminary setting of the state controller.
Thereby, in the case of a plant to be controlled by a state controller, it is advantageously possible to proceed, as a starting basis, from a state controller with a standardized base setting of the control parameters. The standardized base setting or the state controller itself is, for example, selectable from a catalog contained in a memory. By the process according to the invention, a setting, and in particular an optimization, of the control parameters of the state controller can then be performed in a simple way. Thus, the desired control behavior of the closed control circuit is achieved.
It is another advantage of the process of the invention which is based on, from a control-technological standpoint, easily understandable and recognizable setting parameters, that a shift of the poles and thereby an adjustment of the control behavior of the closed control circuit is accomplished. In particular, such setting parameters include amplitude factor, rise time or transient recovery time.